It is known to print images on metal substrates. Typically, it is necessary to coat the metal substrate with a thermoplastic or thermoset material prior to application of ink. It is further known to transfer the ink first to an intermediate carrier and subsequently transfer the ink from the carrier to the coated substrate. See, for example, U.S. Pat. No. 5,994,264 (Sherman et al.).
In particular, it is known to apply paint or ink to a metal coin using a silk screen process. While high quality images may be produced by such processes, adhesion of the image to the coin surface is not adequate to provide sufficient durability to make such coins suitable for public circulation.
A need exists for an efficient and low-cost method of printing images on metal surfaces such that the image demonstrates good adhesion to the metal surface. There is a particular need for a method of printing images on a face of a metal coin, wherein the image demonstrates sufficient durability to make the printed coin suitable for public circulation.